Spring自动注入

文章目录

1. 1. Spring自动注入模型
   1. 1.1. byName
   2. 1.2. byType
   3. 1.3. constructor
   4. 1.4. autodetect

Spring自动注入模型

• No（Spring 默认模式）

  Bean引用需通过 来指明

• byName
• byType

  如果找到多个符合条件，抛出异常;如果没有找到，该属性值不会被设置。

• constructor

  和 byType 类似，应用在构造参数；如果没有找到，报错。

• auotdetect

  通过对 Bean 的内省来选择 constructor 或者 byType。

  1. 是否有带参构造函数，如果有，采用 constructor 模式；否则2.
  2. 只有默认构造函数，将采用 byType。

byName

autowire=”byName”

<bean id="employee" class="com.loogeoustc.beans.EmployeeBean" autowire="byName">
	<property name="fullName" value="loogeoustc"/>
</bean>

   <bean id="departmentBean" class="com.loogeoustc.beans.DepartmentBean" >
       <property name="name" value="Human Resource" />
   </bean>

public class EmployeeBean
{
    private String fullName;
      
    private DepartmentBean departmentBean;
  
    //setter and getter Methods
}


public class DepartmentBean {
    private String name;
    
	//setter and getter Methods
}

byType

autowire=”byType”

1. 加入注解支持
2. 使用 @Autowired

<!--1. 加入注解支持-->
<!--1.a  法1-->
<context:annotation-config />

<!--1.b  法2-->
<bean class ="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor"/>
    
   <bean id="employee" class="com.loogeoustc.byType.EmployeeBean" autowire="byType">
       <property name="fullName" value="Lokesh Gupta"/> 
   </bean>
 
   <bean id="department" class="com.loogeoustc.DepartmentBean" >
       <property name="name" value="Human Resource" />
   </bean>

public class EmployeeBean
{
    @Autowired
    private DepartmentBean departmentBean;
     
    private String fullName;
	
	//setter and getter Methods
}

constructor

autowire=”constructor”

	<context:annotation-config />
   <!--法1:使用 autowire="constructor"-->
   <bean id="employee" class="com.loogeoustc.EmployeeBean" autowire="constructor">
       <property name="fullName" value="Lokesh Gupta"/> 
   </bean>

<!--法2 不使用 autowire="constructor"-->
<bean id="employee" class="com.loogeoustc.EmployeeBean">
    <property name="fullName" value="Lokesh Gupta"/> 
    <constructor-arg>
        <ref bean="department" />
    </constructor-arg>
</bean>
 
   <bean id="department" class="com.loogeoustc.DepartmentBean" >
       <property name="name" value="Human Resource" />
   </bean>

public class EmployeeBean
{
    private String fullName;
    
	private DepartmentBean departmentBean;
 
    public EmployeeBean(DepartmentBean departmentBean)
    {
        this.departmentBean = departmentBean;
    }
     
    //setter and getter Methods
}

autodetect

autowire=”autodetect”

<bean id="employee" class="com.loogeoustc.EmployeeBean" autowire="autodetect">
	<property name="fullName" value="Lokesh Gupta"/> 
</bean>

<bean id="department" class="com.loogeoustc.DepartmentBean" >
	<property name="name" value="Human Resource" />
</bean>